[Glycosylated haemoglobin A1c compared to fasting plasma glucose in outpatients referred to a medical laboratory].

OBJECTIVE Comparing haemoglobin A glycosylate (HbA1c) at different cutoff points for blood glucose measurement to the fasting plasma glucose (FPG) test in outpatients visiting a medical laboratory in the city of Medellin between March and April 2010. METHODS 1,016 blood samples were studied from patients who had been referred to a medical laboratory. Agreement was obtained between tests (Kappa index); sensitivity and specificity were calculated. Different cutoff points for the HbA1c test were also evaluated with the ROC curve. Spearman correlation was used to establish association between FPG and Hb A1c. RESULTS Average HbA1c was 5.7%±0.8 and average FPG was 96 mg/dL±26.1; this was higher in men (99.04±32.7). 75.4% of the samples came within the normal range for diagnosing diabetes with the FPG test, compared to 51.4% with the HbA1c test. The cutoff point where combined sensitivity and specificity presented the best HbA1c value in this study group was 6.2%. DISCUSSION The HbA1c test had high sensitivity and specificity values, so its routine use in diagnosing diabetes mellitus could contribute towards active and early detection of cases to ensure better control of risk factors.